Fabrication and characterization of minor actinides bearing fuels obtained by conventional powder metallurgy process
Résumé
The CEA is currently assessing minor actinides (MA) recycling in nuclear fuels in fast neutrons reactors (FNR). Two routes are investigated: homogeneous recycling, where MA are added up to several percents in UPu-type fuel to be used in the whole core, and heterogeneous recycling, which consists in higher amounts of MA in uranium oxide fuel used in the periphery of the core. The studies include various subject areas: neutronics, thermo-physical properties, coolant type (sodium, lead, bismuth, helium), etc..., and experimental work concerning the fabrication of minor actinides compounds. The first part of this work consisted in the structural study by XRD of AmO2. We studied the lattice parameter change versus time due to α self-irradiation. In this context, AmO2 powder was prepared in the ATALANTE facility in the CEA Marcoule. It is a first approach of swelling phenomenon at the structural scale which has been extended at the macroscopic scale in the second part of the work with the study of the geometrical stability in time of UO2 sintered pellets containing 30% Am. Pellets were fabricated by conventional powder metallurgy process in hot cell at the laboratory scale. Swelling behaviour has been studied by accurate diameter measurements performed along the pellets and correlated to the cumulative α decay dose. Up to 2.1 × 1017 α decay in the sample, no evidence of pellet macroscopic swelling was observed.